import Data.Char

showInt :: Int -> [Char]
showInt n | n < 10 = [ intToDigit n ]
showInt n | otherwise = showInt (n  `div` 10) ++ showInt (n `mod` 10)

go :: [Int] -> [Char]
go [] = ""
go (x:xs) =  showInt x ++ [' '] ++ go xs

doIt :: [Int] -> String
doIt xs = go xs